Reduction of dye stain in processed photographic papers containing dyes



United States Patent REDUCTION OF DYE STAIN IN PROCESSED ggggoomrucPAPERS CONTAINING Walter J. Weyerts, Rochester, N. Y., assignor toEastman Kodak Company, Rochester, N. Y., a corporation of New Jersey NoDrawing. Application August 1, 1952, Serial No. 302,237

5 Claims. (Cl. 95-88) y This invention relates to the reduction of dyestain in processed photographic papers containing sensitizing dyes bythe addition of aryl or alkaryl sulfonic acids or their water-solublesalts to the stop bath or the fixing bath which are employed inprocessing those papers.

The emulsions employed for photographic papers often contain sensitizingdyes and many of the dyes of this nature have a tendency to introducestain into the paper upon the processing of those papers. This effecthas been noted, for instance, in the case of papers for producing directpositive photographs, for example, of the type described in U. S. PatentNo. 2,497,875 of George E. Falleson. Also, in cases where dyes have beenused in higher than normal concentration, or in some cases of specialprocessing, my invention finds application. Types of sensitizing dyeswhich, when used in photographic paper emulsions, have a tendency tostain the paper upon its processing are acid type dyes such as themerocyanines, the eosins, the oxonols and the acid azo dyes, such asCongo red and Glycine red.

One object of my invention is to provide a procedure for processingphotographic paper in which staining of the paper by the sensitizing dyein the photographic emulsion used is substantially eliminated. Anotherobject of my invention is to provide a method for processingphotographic papers in which an aryl or alkaryl sulfonic acid or itssoluble salt is employed in the stop bath or the fixing bath in whichthe paper is processed. A further object of my invention is to preventstaining of photographic paper in the machine processing of photographicpaper in which the washing time is relatively short (such as less than 4minutes). Where a relatively long time of washingis employed, such as onthe order of minutes, staining of the paper is negligible. Other objectsof my invention will appear herein.

In the use of photographic papers, the paper is exposed, therebyproducing a latent image in the emulsion thereof. The paper ordinarilyis then put through a development bath to bring out the image, followedby immersion in an acid stop bath to end the development and then in afixing bath to fix the print so obtained. It has been found that, withcertain types of dyes, a short washing time, as used in machineprocessing, contributes to staining of the paper by those dyes, and, toprevent or minimize such staining, an aryl sulfonic acid, an alkarylsulfonic acid or a soluble salt of one of these is added to the acidstop bath or to the fixing bath in accordance with my invention.

Some of the sulfonates which have been found to be especially useful inaccordance with my invention are sodium anthraquinone-beta-sulfonate,sodium anthraquinone-alpha-sulfonate and sodium mterephenyl-4-sulfonate. For instance, the use of sodiumanthraquinonebeta-sulfonate in an acid stop bath in a concentration of0.5% almost completely eliminated dye stain in processed paper, and theother sulfonates mentioned were substantially equally eflective. Othercompounds which exhibited a stain-reducing effect when used in the acidstop ice bath or in the fixing bath in addition to those mentioned abovewere naphthalene sulfonic acids, naphthol sulfonic acids, napthyl aminesulfonic acids, alkyl naphthalene sulfonic acids, diphenyl disulfonicacids, p-toluen'e sulfonic acids and salts thereof. Another materialwhich is effective is Tamol, which is the sodium salft of naph= thalenesulfonic acid condensed with formaldehyde.

These sulfonates or sulfonic acids are generally effective inconcentrations within the range of 0.l-l but higher concentrations thanthe range given can be employed in stop baths or fixing baths inaccordance with my invention, and in some cases the use of higherconproximately 1 minutes.

centrations than 1% are even preferred, such as where dye staining isespecially pronounced.

The processing of a photographic paper, such as of the type described inPatent No. 2,497,875 of Falleson, may be carried out by developing thatemulsion layer, after its exposure, in a developer of the type disclosedand claimed in application Serial No. 218,071 of Russell and Haist, nowU. S. Patent 2,625,475, such as for ap- After this development the paperis placed in an acid stop bath, suchas a 3% aqueous solution of citricacid or acetic acid, such as for approximately A minute. The paper isthen placed in a fixing bath, such as for approximately 2 minutes, whichbath may have a formula as follows:

FIXING BATH Grains Sodium thiosulfate (hypo) a r rr; r 300.0 Sodiumbisulfite a- 7.5 Sodium sulfite (desiccated) 7.5 Sodium citrate 2.0Ammonium sulfate 30.0

Water to make 1 liter The paper is then washed, such as in runningwater, forapproximately 2 /2 minutes and dried. Without the benefit ofmy invention (unless long-time washing is used), the final printsordinarily exhibit an objectionable amount of dye stain. The followingexamples of stop or fixing baths which can be employed in accordancewith my invention to prevent the dye staining in the processingdescribed are illustrative:

Example 1 Example 2 A photographic paper was processed as describedabove, however, a stop bath consisting of an aqueous solution of citricacid, 3% concentration and 0.5% of sodium rn-diphenylbenzene sulfonatewas employed. After fixing, washing and drying, a paper was obtainedsubstantially free from dye stain.

Example 3 A photographic paper, after exposure, was processed asdescribed above using as the stop bath therein an aqueous solutioncontaining 3% of citric acid and 1% of dibutyl phenyl phenol sodiumdisulfonate. The paper obtained had little or no noticeable dye staintherein.

Example 4 An exposed photographic paper was processed as describedabove, but a fixing bath having the Water to make 1.0 liter Afterfixing, the paper was then washed and dried, and was found to be free ofany appreciable stain from the sensitizing dye employed inthephotographic emulsion.

I claim:

1. In the processing of silver halide sensitized papers containingsensitizing dyes in which the paper after exposure is developed, fixedand washed, the method of reducing .dye stain in the processed, washedand dried paper which comprises treating'the paper in the processingoperation between the developing and final washing steps with a fixingbath containing in solution therein a compound selected from the aryland alkaryl sulfonic acids and their water soluble salts.

2. In the processing of silver halide sensitized papers containingsensitizing dyes in which the paper after exposure is developed, fixedand washed, the method of reducing dye stain in the processed, washedand dried paper which comprises treating the paper in the processingoperation between the developing and final washing steps with a fixingbath containing sodium anthraquinone-psulfonate.

3. In the processing of silver halide sensitized papers containingsensitizing dyes in which the paper after exposure is developed, fixedand washed, the method of reducing dye stain in the processed, washedand dried paper which comprises treating the paper in the processingoperation between the developing and final washing steps with a fixingbath containing sodium m-terephenyl-4'- sulfonate.

4. In the'processing of silver halide sensitized papers containingsensitizing dyes in which the paper after exposure is developed, fixedand washed, the method of reducing dye stain in the processed, washedand dried paper which comprises treating the paper in the processingoperation between the developing and final washing steps with a fixingbath containing sodium m-diphenyl benzene snlfonate.

5. In the processing of silver halide sensitized papers containingsensitizing dyes in which the paper after exposure is developed, fixedand washed, the method of reducing dye stain in the processed, washedand dried paper which comprises treating the paper in the processingoperation between the developing and final washing steps with a fixingbath containing monobutyl diphenyl sodium sulfonate.

References Cited in the file of this patent UNITED STATES PATENTS2,322,084 Young et a1. June 15, 1943 2,367,516 Muehler et a1. Jan. 16,1945 2,428,208 Edgerton Sept. 30, 1947 2,440,954 Jennings May 4, 19482,453,347 Russell Nov. 9, 194-8 2,578,075 Kienast Dec. 11, 19512,615,807 Umberger Oct. 28, 1952

1. IN THE PROCESSING OF SILVER HALIDE SENSITIZED PAPERS CONTAININGSENSITIZING DYES IN WHICH THE PAPER AFTER EXPOSURE IS DEVELOPED, FIXEDAND WASHED, THE METHOD OF REDUCING DYE STAIN IN THE PROCESSED, WASHEDAND DRIED PAPER WHICH COMPRISES TREATING THE PAPER IN THE PROCESSINGOPERATION BETWEEN THE DEVELOPING AND FINAL WASHING STEPS WITH A FIXINGBATH CONTAINING IN SOLUTION THEREIN A COMPOUND SELECTED FROM THE ARYLAND ALKARYL SULFONIC ACIDS AND THEIR WATER SOLUBLE SALTS.